This won't get you that muscle definition as it looks like your routine consists of mainly cardio. You will need to add some strength training in there, or you are in danger of looking "skinny fat", i.e. skinny but muscle has also wasted away. Google "Strength training for women" or something, and have a look at the difference between those that don't do it, and those that do.
On the fitness (cardiovascular) side, this looks excellent, if that is your goal.
On the muscle definition side, add about 2- 3 days a week of strength training. Even the very slim VS models do it or they would have flabbiness everywhere and no ass.
Sit ups are not the best way to get abs, compound exercises are, as well as other core exercises like planks, and also things like russian twists and bicycle crunches. And you really only have to do this about 3 times a week to see abs (if, like 2CAN said, you get your body fat% right)
But again, you need muscle otherwise your body fat percentage being low is a pip dream.